Primary peritoneal mesotheliomas in children: a clinicopathological and immunohistochemical study of eight cases

Pediatric, Adolescent and Young Adult (AYA) Peritoneal and Pleural Mesothelioma: A National Cancer Database Review

PURPOSE

Malignant peritoneal and pleural mesothelioma are rare in young patients, with a paucity of data regarding clinical characteristics and outcomes. We aimed to describe the clinical characteristics, treatment strategies, and outcomes for pediatric and adolescent/young adult (AYA) patients.

METHODS

The National Cancer Database (NCDB) was queried for malignant peritoneal and pleural mesothelioma in pediatric and AYA patients (ages 0-39) from 2004 to 2019. Stratification was performed for pediatric (age 0-21) and young adult (age 22-39) patients. Chi-squared, multivariable cox regression, and Kaplan-Meier analyses were performed.

RESULTS

We identified 570 total patients, 46 pediatric and 524 young adult, with mesothelioma (363 peritoneal and 207 pleural). There were significant differences in sex distribution as patients with peritoneal mesothelioma were more frequently female (63.1%). Patients with peritoneal mesothelioma were more likely to have radical surgery compared to pleural mesothelioma (56.7% v. 24.6%, respectively). A majority of patients with peritoneal and pleural mesothelioma received chemotherapy (66.4% and 61.4%, respectively). For peritoneal mesothelioma, surgical resection was associated with improved overall survival, whereas male sex, neoadjuvant chemotherapy, and radiation were associated with worse overall survival. For pleural mesothelioma, intraoperative chemotherapy was associated with improved overall survival, whereas Black race was associated with worse overall survival. Mean overall survival was greater for patients with peritoneal mesothelioma (125 months) compared to those with pleural mesothelioma (69 months), which remained significant after stratification of pediatric and young adult patients.

CONCLUSION

By analyzing a large cohort of pediatric and AYA mesothelioma, this study highlights clinical, prognostic, and survival differences between peritoneal and pleural disease.

LEVEL OF EVIDENCE

Level III.

TYPE OF STUDY

Retrospective.

Mesotheliomas in Children

Mesotheliomas are rare and aggressive tumors that originate from mesothelial cells. Although exceedingly rare, these tumors may occur in children. Different from adult mesotheliomas, however, environmental exposures particularly to asbestos do not appear to play a major role in mesotheliomas in children, in whom specific genetic rearrangements driving these tumors have been identified in recent years. These molecular alterations may increasingly offer opportunities for targeted therapies in the future, which may provide better outcomes for these highly aggressive malignant neoplasms.

Peritoneal Mesothelioma-An Update

A remarkable amount of new information has been generated on peritoneal mesothelioma (PeM), ranging from nomenclature changes, including the removal of "malignant" when referring to this neoplasm and the use of the term "tumor" rather than "mesothelioma" to designate the neoplasm formerly known as "well-differentiated papillary mesothelioma", to the acknowledgment that PeMs can be associated with tumor predisposition syndromes or germline mutations. Although the disease is still more frequently seen in caucasian males, PeM is not uncommon in women. In addition, it can represent a diagnostic challenge when it has an uncommon presentation (ie, paraneoplastic syndrome or incidental finding) or when it has confounding histologic features. Ancillary testing, including immunohistochemical stains, in situ hybridization for CDKN2A or NF2 , and molecular studies, in selected cases, allows its correct diagnosis. The molecular landscape of PeM is still a work in progress; however, some findings, such as ALK gene rearrangements and EWSR1/FUS-ATF1 fusions, are specifically seen in PeM of young patients. The biological behavior of PeM is variable; however, cytoreductive surgery and hyperthermic intraperitoneal chemotherapy have markedly improved the survival of patients affected by this disease.

Pediatric Malignant Peritoneal Mesothelioma With Meningeal Metastasis

Malignant peritoneal mesothelioma (MPM) is an extremely rare entity with a poor prognosis. We report on a 16-year-old boy with ascites and abdominal distension. A computed tomography scan showed peritoneal thickening and a mass adjacent to the transverse colon. Neither repeated cytologic testing of ascitic fluid, nor peritoneal tissue biopsy detected malignant cells. After the patient became progressively comatose, a magnetic resonance imaging scan of the brain showed leptomeningeal enhancement. An autopsy showed MPM infiltrating the pleura and the meninges. This is the first report on meningeal metastasis of MPM in a pediatric patient illustrating the enigmatic behavior of the tumor and highlighting the diagnostic pitfalls.

Metastatic Malignant Peritoneal Mesothelioma Mimicking an Autoinflammatory Syndrome in a 12-Year-Old Boy

A case of a malignant peritoneal mesothelioma mimicking an autoinflammatory syndrome in a 12-year-old boy is reported. The patient initially presented with lymphadenopathy and weight loss but without abdominal pain. Three things confounded the initial diagnosis: a positive test result for a gene related to cryopyrin-associated periodic syndrome, a positive response to the autoinflammatory syndrome treatment, and a lymph node biopsy which showed "hyperplastic mesothelial cells in the lymph sinuses." His symptoms relapsed several years later, and a peritoneal biopsy confirmed the final diagnosis. Complete morphological, immunohistochemical, and molecular diagnoses are described. A translocation in the TERT gene involving the truncation of the promoter was found in the mesothelioma. The translocation has never been described in mesotheliomas and is of an unknown significance.

Molecular characterization of diffuse malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma is a rare aggressive tumor that arises from the peritoneal lining. While recurrent BAP1 mutations have been identified in a subset of mesotheliomas, molecular characteristics of peritoneal mesotheliomas, including those lacking BAP1 alterations, remain poorly understood. Using targeted next-generation sequencing, we examined the molecular features of 26 diffuse malignant peritoneal mesotheliomas. As part of an exploratory analysis, we analyzed an additional localized peritoneal mesothelioma and one well-differentiated papillary mesothelioma with invasive foci. Genomic characterization identified categories of diffuse malignant peritoneal mesotheliomas: The first group included 18 (69%) tumors with recurrent BAP1 alterations, with eight (31%) having more than one BAP1 alterations, and concomitant alterations in PBRM1 (46%) and SETD2 (35%). All tumors with complete loss of BAP1 expression by immunohistochemistry harbored BAP1 molecular alterations. PBRM1 alterations were significantly enriched in the BAP1-altered cohort. Frequent copy number loss of BAP1, ARID1B, PRDM1, PBRM1, SETD2, NF2, and CDKN2A was noted. The second group included eight (31%) BAP1-wild-type tumors: two with TP53 mutations, one with a TRAF7 activating mutation, one with a SUZ12 inactivating mutation, and three with ALK rearrangements that we previously published. One TP53-mutant biphasic mesothelioma showed evidence of genomic near-haploidization showing loss of heterozygosity of all chromosomes except 5, 7, 16, and 20. The localized peritoneal mesothelioma harbored a nonsense CHEK2 mutation, and the well-differentiated papillary mesothelioma with invasive foci harbored no reportable variants. In conclusion, we described the genetic categories of diffuse malignant peritoneal mesotheliomas, with BAP1-mutant and BAP1-wild-type groups. Our findings implicated DNA repair, epigenetics, and cell cycle regulation in the pathogenesis of peritoneal mesotheliomas, with identification of potential therapeutic targets.

Multicystic and diffuse malignant peritoneal mesothelioma in children

BACKGROUND

Malignant and multicystic peritoneal mesotheliomas are extremely rare tumors in children, developing from mesothelial cells. No specific guidelines are available at this age.

METHODS

We performed a retrospective analysis of all identified children (< 18-year-old) treated in France from 1987 to 2017 for a diffuse malignant peritoneal mesothelioma (DMPM) or a multicystic peritoneal mesothelioma (MCPM).

RESULTS

Fourteen patients (5 males and nine females), aged 2.2 to 17.5 years, were included. The most frequent presenting symptoms were abdominal pain, ascitis, and alteration in the general condition. Eight patients had epithelioid mesothelioma, three had biphasic mesothelioma, and three had MCPM. Eight patients with DMPM diagnosis received cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). Among them, six patients had neoadjuvant systemic chemotherapy, one patient, post-operative chemotherapy, and one patient CRS and HIPEC only. Three patients received only systemic chemotherapy. All patients with MCPM had only surgery. After a median follow-up of seven years (2-15), six patients (6/11; one death) with DMPM and two patients (two/three) with MCPM had a local and distant recurrences.

CONCLUSION

Peritoneal mesothelioma in children is a rare condition with difficult diagnosis and high risk of recurrence. Worldwide interdisciplinary collaboration and networking are mandatory to help diagnosis and provide harmonious treatment guidelines.

Clinicopathologic and genetic characteristics of young patients with pleural diffuse malignant mesothelioma

Pleural diffuse malignant mesothelioma typically presents during the seventh decade of life and has poor prognosis. Recent epidemiologic studies have shown differences between young and older mesothelioma patients, but the biology of pleural mesothelioma in young patients is poorly understood. We studied the clinicopathologic and genetic characteristics in pleural mesothelioma patients aged 35 years and younger. Thirty-six consecutive pleural mesothelioma patients aged 35 years and younger were compared with 48 older patients. We examined demographic and clinical characteristics, histologic type, growth patterns, mitotic index, and nuclear grade on hematoxylin and eosin-stained slides, BAP1 protein expression by immunohistochemistry, and CDKN2A and NF2 deletions by fluorescence in situ hybridization. Clinicopathologic and cytogenetic results were compared between young and older groups, and correlated with overall survival. Young patients were more frequently women, reported less asbestos exposure, and had a greater frequency of prior therapeutic radiation and family history of breast cancer than older patients (P<0.05 each). There were no histologic differences between young and older patients (all P>0.05). CDKN2A deletion was less prevalent in young patients (P=0.01), loss of BAP1 protein expression less frequent in young patients (P=0.06), and NF2 deletion rates similar between groups (P>0.05 each). Median overall survival was 40 vs 26 months (P=0.10) in young and older patients, respectively, and 47 vs 31 months (P=0.04) when comparing patients with epithelioid histology only. High mitotic index and non-epithelioid histology were the only characteristics associated with a poor overall survival in young patients. Young patients with pleural mesothelioma have an equal sex distribution and are more likely to have a history of mantle radiation, family history of breast cancer, and lower rates of CDKN2A deletion than older patients. Our results suggest that pleural mesothelioma in young patients has distinctive clinical and genetic characteristics, despite some similarities to pleural mesothelioma in older patients.

Keratin 5 overexpression is associated with serous ovarian cancer recurrence and chemotherapy resistance

This study investigated the clinical significance of keratin 5 and 6 expression in serous ovarian cancer progression and chemotherapy resistance. KRT5 and KRT6 (KRT6A, KRT6B & KRT6C) gene expression was assessed in publically available serous ovarian cancer data sets, ovarian cancer cell lines and primary serous ovarian cancer cells. Monoclonal antibodies which detect both K5/6 or only K5 were used to assess protein expression in ovarian cancer cell lines and a cohort of high grade serous ovarian carcinomas at surgery (n = 117) and after neoadjuvant chemotherapy (n = 21). Survival analyses showed that high KRT5 mRNA in stage III/IV serous ovarian cancers was significantly associated with reduced progression-free (HR 1.38, P < 0.0001) and overall survival (HR 1.28, P = 0.013) whilst high KRT6 mRNA was only associated with reduced progression-free survival (HR 1.2, P = 0.031). Both high K5/6 (≥ 10%, HR 1.78 95% CI; 1.03−2.65, P = 0.017) and high K5 (≥ 10%, HR 1.90, 95% CI; 1.12−3.19, P = 0.017) were associated with an increased risk of disease recurrence. KRT5 but not KRT6C mRNA expression was increased in chemotherapy resistant primary serous ovarian cancer cells compared to chemotherapy sensitive cells. The proportion of serous ovarian carcinomas with high K5/6 or high K5 immunostaining was significantly increased following neoadjuvant chemotherapy. K5 can be used to predict serous ovarian cancer prognosis and identify cancer cells that are resistant to chemotherapy. Developing strategies to target K5 may therefore improve serous ovarian cancer survival.

Imaging of the pediatric peritoneum, mesentery and omentum

The normal peritoneal structures, including the mesenteries and the omenta, are only a few cell layers thick and are visible on imaging based upon the tissues (e.g., fat) and structures (e.g., blood vessels and lymph nodes) contained within them. These structures become more visible and change in appearance when involved by pathological processes. In this pictorial essay, we discuss the normal anatomy of the various abdominopelvic peritoneal structures and illustrate numerous developmental and acquired diagnoses that involve these structures in the pediatric and young adult population.

Malignant Peritoneal Mesothelioma in an Adolescent Male With BAP1 Deletion

Diffuse malignant peritoneal mesotheliomas in children are uncommon, aggressive tumors with a grave prognosis. We herein report the clinical, radiologic, and pathologic findings of a 16-year-old male. The adolescent presented with a history of abdominal pain, nausea and daily, nonbilious, nonbloody emesis for 3 weeks. Radiographic imaging suggested small bowel obstruction. The diagnostic work-up and differential diagnoses are discussed. Histologically, the tumor was composed of epithelioid cells with a papillary and glandular architectural pattern. A few glands appeared to produce mucinous material. Histochemistry revealed PAS diastase resistant mucin, an inconspicuous finding in diffuse malignant peritoneal mesothelioma. An extensive immunohistochemistry panel (calretinin, WT-1, D2-40, CK 7, CAM 5.2, CK 5/6, CEA, B72.3, CK 20, CD10, CD30, CD15, CD117, PLAP, S100, TFE3, and EMA) confirmed the diagnosis. Of special interest, BAP1 staining was cytoplasmic and consistent with 3p deletion detected by conventional cytogenetics. The ultrastructural analysis demonstrated long microvilli, desmosomes, and intercellular junctions which further supported the diagnosis.

An 8-Year-Old Child with Malignant Deciduoid Mesothelioma of the Abdomen: Report of a Case and Review of the Literature

Malignant mesothelioma is an uncommon tumor that usually arises in the pleural cavity of adults with a history of asbestos exposure. Less frequently, it appears in the peritoneum or other mesothelial surfaces. Deciduoid mesothelioma is a rare subtype that has been found at both sites. Of the 3 reported cases in children, 2 originated in the mesenterium and 1 in the pleura. We describe a 4th case of pediatric, malignant, deciduoid mesothelioma and a third case in the mesenteric cavity. The patient was an 8-year-old girl who presented with abdominal pain and fullness. Workup revealed extensive involvement of the abdomen by a serosa-based tumor. The clinical and pathologic findings are described, and the pertinent literature is reviewed.

Miscellaneous conditions of the peritoneal cavity--peritoneal tumors, pseudomyxoma, mesothelioma, fibroblastic reaction, cocoon, cystic lymphatic malformations, blue-bleb, and chylous ascites

The peritoneum is subject to both primary neoplasia and secondary malignancy from direct, trans-coelomic, or hematogenous spread from any cancer. The knowledge base in the pediatric age group is very limited due to the rarity of peritoneal conditions in children, and much of the information is extrapolated from adult literature. There have been few reports in the pediatric population on the diagnosis and management of peritoneal conditions including peritoneal malignancy. In this article, we aim to highlight some of these conditions and the treatments available with a special emphasis on the evolving role of cytoreduction surgery and hyperthermic intraperitoneal chemotherapy in the treatment of certain peritoneal malignancies in children.

Clinical, histologic, and genetic features of mesothelioma in a 7-year-old child

Malignant mesothelioma (MM) is a highly aggressive malignancy that is extremely rare in children. This case report documents a 7-year-old male without previous asbestos exposure with peritoneal MM that initially responded to chemotherapy with cisplatin and gemcitabine but ultimately metastasized to his chest. He was diagnosed with MM based on histology, extensive immunohistochemical analyses, and an elevated serum CA-125 level. Cytogenetics and comparative genomic hybridization (CGH) analysis of his tumor identified a single extra copy number of chromosome 11 with few other changes noted.

Malignant biphasic peritoneal mesothelioma in a child: fine-needle aspiration cytology, histopathology, and immunohistochemical features along with review of literature

Peritoneal mesotheliomas in children are of rare occurrance. We herein report the clinical, radiological, and pathological findings of a rare case of malignant peritoneal mesothelioma occurring in nine-year-old female child. The child presented with abdominal distension and awareness of a painless mass in the abdomen which on radiology appeared as a large heterogeneous pelvic mass with peritoneal deposits at multiple sites. To the best of our knowledge, this is the first case of a peritoneal malignant mesothelioma on which fine needle aspiration (FNA) was performed as first line investigation of the primary tumor. The cytological features, major differential diagnoses, and the pitfalls therein are discussed. Histopathology revealed biphasic pattern of mesothelioma which is again a rare pattern. Immunochemistry was carried out on the cell block made from the FNA as well as the biopsy specimen essentially showed the same features. There was positivity for vimentin, EMA, and cytokeratin 5/6 while WT1, calretinin, and CEA were negative; however, D2-40 showed diffuse membranous positivity in the epithelial areas and cytoplasmic positivity in the spindle areas confirming a mesothelioma. We emphasize the use of immunochemistry on cell block material for a confident diagnosis of mesothelioma in such cases.

Treatment of peritoneal mesothelioma in pediatric patients

Peritoneal mesothelioma is a rare and often aggressive malignancy, mostly affecting asbestos exposed adults. We present four pediatric peritoneal cases treated with a cisplatin-based doublet regimen, the standard of care in the systemic therapy of adult mesothelioma. Treatment was well tolerated, and three of these patients have achieved long-term survival. The fathers of three of the patients worked in the construction industry and may have been the source of indirect asbestos exposure.